J45.21 Mild intermittent asthma with (acute) exacerbation

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from J45 Asthma

Includes

• allergic (predominantly) asthma
• allergic bronchitis NOS
• allergic rhinitis with asthma
• atopic asthma
• extrinsic allergic asthma
• hay fever with asthma
• idiosyncratic asthma
• intrinsic nonallergic asthma
• nonallergic asthma

Excludes1 (never code together)

• detergent asthma (J69.8)
• miner's asthma (J60)
• wheezing NOS (R06.2)
• wood asthma (J67.8)

Excludes2 (not included here)

• asthma with chronic obstructive pulmonary disease (J44.89)
• chronic asthmatic (obstructive) bronchitis (J44.89)
• chronic obstructive asthma (J44.89)
• other specified chronic obstructive pulmonary disease (J44.89)

Use additional code

• code to identify:
• eosinophilic asthma (J82.83)
• exposure to environmental tobacco smoke (Z77.22)
• exposure to tobacco smoke in the perinatal period (P96.81)
• history of tobacco dependence (Z87.891)
• occupational exposure to environmental tobacco smoke (Z57.31)
• tobacco dependence (F17.-)
• tobacco use (Z72.0)

Risk adjustment (HCC)

• RxHCC V08: HCC 229 — Chronic Obstructive Pulmonary Disease, Bronchiectasis, and Other Asthma

MS-DRG index

Defines the logic of DRG(s) 202-203 in MDC 04.

Approximate ICD-9-CM (GEMs)

• 493.02 Extrinsic asthma with (acute) exacerbation (approximate)
• 493.12 Intrinsic asthma with (acute) exacerbation (approximate)

Code annotations containing back-references to J45.21

Back-references to J45.2

• Code First: J82.83 Eosinophilic asthma ("mild intermittent asthma (J45.2-)")

Back-references to J45

• Code First: F54 Psychological and behavioral factors associated with disorders or diseases classified elsewhere ("asthma (J45.-)")
• Code Also: J44 Other chronic obstructive pulmonary disease ("type of asthma, if applicable (J45.-)")
• Type 1 Excludes: J98.01 Acute bronchospasm ("asthma (J45.-)")
• Type 1 Excludes: R06.2 Wheezing ("Asthma (J45.-)")

Diagnosis Index entries for J45.21

• Asthma, asthmatic (bronchial) (catarrh) (spasmodic) › intermittent (mild) › with › exacerbation (acute)
• Asthma, asthmatic (bronchial) (catarrh) (spasmodic) › mild intermittent › with › exacerbation (acute)

Nearby codes

• J45 Asthma
• J45.2 Mild intermittent asthma
• J45.20 Mild intermittent asthma, uncomplicated
• J45.21 Mild intermittent asthma with (acute) exacerbation (this code)
• J45.22 Mild intermittent asthma with status asthmaticus
• J45.3 Mild persistent asthma
• J45.30 Mild persistent asthma, uncomplicated
• J45.31 Mild persistent asthma with (acute) exacerbation
• J45.32 Mild persistent asthma with status asthmaticus